Heteroleptic Ag(I) Complexes Bearing Benzothiazole and Benzoxazole Ligands for Orange‐Red Light‐Emitting Electrochemical Cells

Abstract

Optoelectronic devices based on metal complexes alternative to platinum group metals are highly sought, yet their design remains very challenging. In this framework, electroactive silver complexes have been largely overlooked to date. Herein, a family of orange phosphorescent mononuclear cationic Ag(I) complexes of general structure [Ag(N1^N2)(P^P)]PF6, where N1^N2 is a (o‐methyl)pyridyl‐, quinolyl‐ or pyrazyl‐ functionalized benzo(x)azole (x = thio‐ or ox‐) and P^P is either DPEphos or Xantphos, is unraveled. The complexes display emission arising from a triplet ligand centered (3LC) excited state located on the N1^N2 ligand. Interestingly, the compounds display high photoluminescence quantum yield (PLQY) in solid state and, for derivative 3b, a value as high as 14% was recorded in CH2Cl2 solution. Their use as electroactive materials in LECs is also demonstrated, with complexes 1b and 3b providing devices with peak external quantum efficiencies (EQE) as high as 3.5 and 2.5% respectively in the orange‐red region of the visible spectrum, enhanced carrier balance, and limited temporal variation of the electroluminescence (EL) profile. The photophysical investigation of these complexes is further accompanied by (time‐dependent) density functional theory (TD‐DFT) calculations, which unravel multiple scenarios behind the exciton‐assisted non‐radiative quenching pathways typical of these Ag(I) complexes.